Pink and blue boxes are colliding while green and blue are not for instance.
Given the following interface which exposes a method
collide
which takes a non-modifiable
Collidable
as a parameter returns true if
caller
collides with the given
Collidable
parameter.
public interface ICollidable {
public boolean collide(ICollidable c);
}
Create a class
Box
and implements
ICollidable
and stores fields describing a 2D box in space.
Two boxes collide if they share some portion on the space.
This is a blurry definition, you have to come up with a more formal and mathematical description of what collision means.
Box
must also override the
toString
method from
Object
superclass.
The following image gives you a (big) hint on how to formalize collisions in two 2D.
Pink and blue boxes are colliding while green and blue are not for instance.
Create a class Arena which stores information about a set of Collidable Objects and exposes a method with the following signatures.
Arena
stores an array of
Collidable
which size (can be assumed) never exceed
1000
;
public void checkCollisions(){
}
@Override
public String toString() {
}
checkCollisions
should check for all collision between all
ICollidable
objects. On the event of a collision between two objects
A and B
it should print the following:
System.out.println("Collision: " + A.toString() + " "+ B.toString());
toString
takes care of drawing the Arena to standard output (console). Draw the boundaries of the Area using the plus
+
, character.
Boxes must be drawn using the point
.
character and corner using the
+
character.
You can always assume that Collidable Objects coordinates are never lower than
0
or greater than
99
.
In order to test out collision detection system, you should also provide a
init
function which inits boxes randomly (within arena boundaries) and a main which will execute a demo.
public static void main(String[] args) {
Arena a = new Arena();
a.initArena(10); //initialize arena with 10 random Box
System.out.println(a.toString()); // Print the Arena
a.checkCollisions(); // Detect collisions and print them out on stdout
}
//init arena should init boxes randomly.
public void initArena(final int NO){
Random r = new Random(System.currentTimeMillis());
objects = new Box[NO];
for(int i=0; i<NO; i++){
//function that creates a random box
Box br=createRandomBox(r,....);
objects[i] =br;
}
}
The following is the kind of result you should aim to obtain.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ +
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+ +
+ +..................................+ +
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+ . +....+ . +
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+ . . . . +
+ . . . . +
+ . . . . +
+ +..................................+ +
+ . . +
+ . . +
+ +...........................................................+ +
+ . +....+ . +
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+ +...........................................................+ +
+ +
+ +.+ +
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+ . . +
+ . . +
+ . . +
+ . . +
+ +.................................................................+ . . +
+ . . . . +
+ . . +.+ +
+ . . +
+ +.................................................................+ +
+ +
+ +
+ +
+ +
+ +
+ +
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+ +
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+ +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Collision: 60:49-5:10 19:58-60:14
Collision: 60:49-5:10 52:10-35:45
What is the complexity of the
checkCollision
method?
Do you think it can be used in a game?
Can it be used in a game, even if the number of objects is, more than 1000?